CeO2@Au核壳结构纳米粒子的合成与性质研究

采用沉淀法制备了球形CeO2纳米粒子,将其作为核粒子溶液,然后向其中滴加四氯合金酸溶液,在CeO2胶体表面利用柠檬酸钠还原[AuCl4]-离子,得到了CeO2@Au核壳结构纳米粒子。TEM分析表明,CeO2纳米粒子分散效果好,粒径为5 nm;CeO2@Au核壳粒子为球形,无团聚,平均粒径为15 nm。XRD分析表明,CeO2@Au核壳粒子为晶型结构,属于立方晶系,CeO2空间群为O5H-FM3M,Au的空间群为Fm-3m。UV-vis分析发现,CeO2@Au核壳粒子在300和520 nm处呈现出两个比较强的吸收峰,分别对应于CeO2胶体溶液的吸收峰和金粒子的表面等离子共振吸收峰。EDS分析了核壳结构CeO2@Au纳米粒子中存在Ce,O和Au 3种元素。XPS分析表明,Ce3d3/2和Au4f电子结合能与标准结合能相比发生了变化,说明CeO2与Au之间存在着相互作用。     

粒径可控纳米CeO_2的微乳液法合成

以十六烷基三甲基溴化铵(CTAB)/正丁醇/正辛烷/硝酸铈(Ce(NO3)3)水溶液(氨水)所形成的反相微乳液体系合成CeO2前驱体,利用热重(TG)和X射线衍射(XRD)分析方法确定了得到纳米CeO2的适宜焙烧温度为550℃,CeO2前驱体经550℃焙烧后得到纳米CeO2.采用XRD、透射电镜(TEM)、紫外-可见(UV-Vis)分光光度计等表征手段分别对纳米CeO2的晶形、形貌、粒径及紫外吸收性质进行了表征,该纳米CeO2粒子具有立方晶型结构,分散性较好、粒径范围为5-18nm.考察了微乳液中正辛烷与正丁醇质量比、Ce(NO3)3浓度对纳米CeO2粒径的影响,结果表明:利用微乳液法,通过改变微乳液中正辛烷与正丁醇质量比、Ce(NO3)3浓度能够对纳米CeO2粒径进行有效控制;纳米CeO2的粒径均随着正辛烷与正丁醇质量比和Ce(NO3)3浓度的增大而减小.同时,对不同条件下制得的纳米CeO2的紫外吸收性质进行了考察.     

单相Ce0.5Zr0.5O2立方固溶体的高压高温合成

以化学沉淀法制备的 Ce O2 和 Zr O2 纳米微粒为前驱体 ,首次在高压高温 (3 .1 GPa,1 0 73 K)下合成了单相 Ce0 .5Zr0 .5O2 面心立方固溶体 .使用 X射线衍射、TG-DTA、XPS、Raman、电子自旋共振谱和交流阻抗谱等对样品的结构、Ce离子的价态和导电性进行了表征 .实验结果表明 ,纳米 Ce O2 -50 % Zr O2 混合物在高压 (0 .9GPa以上 )高温 (1 0 73 K以上 )条件下可以发生固态反应 ,高压下固溶温度明显降低 .Ce0 .5Zr0 .5O2 面心立方固溶体在 773 K以下是热稳定的 ,不发生结构转变 ,固溶体中 Ce离子完全以 Ce4 + 形式存在 ,773 K退火也不引起 Ce4 + 向 Ce3 + 转变 ,晶格中氧缺位非常少 .Ce0 .5Zr0 .5O2 面心立方固溶体是离子导电 ,82 3 K时电导率 σ=1 .2× 1 0 -5S/cm,与纯 Ce O2 在同温度下的电导率同数量级 ;1 1 2 3 K时 σ=2 .1× 1 0 -3 S/cm,小于掺入稀土或碱土氧化物的氧化锆和氧化铈基电解质的电导率 .在高温区和低温区 ln(σT)与 1 /T的关系满足斜率不同的二条直线 ,低温活化能小于高温活化能 .固溶体的显微硬度 (50 g载荷 )为 572 HV.     

Density functional studies of model cerium oxide nanoparticles

Density functional plane-wave calculations have been performed to investigate a series of ceria nanoparticles (CeO2-x)(n), n Ce3+ reduction have been accounted for through the use of an effective on-site Coulomb repulsive interaction within the so-called DFT+U approach. Twelve nanoparticles of up to 2 nm in diameter and of both cuboctahedral and octahedral forms are chosen as representative model systems. Energetic and structural effects of oxygen vacancy formation in these nanoparticles are discussed with respect to those in the bulk and on extended surfaces. We show that the average interatomic distances of the nanoparticles are most significantly affected by the creation of oxygen vacancies. The formation energies of non-stoichiometric nanoparticles (CeO2-x)(n) are found to scale linearly with the average coordination number of Ce atoms; where x < 0 species, containing partially reduced O atoms, are less stable. The stability of octahedral ceria particles at small sizes, and the predicted strong propensity of Ce cations to acquire a reduced state at lower coordinated sites, is supported by interatomic potential-based global optimisations probing the low energy isomers of the Ce19O32 nanoparticle.     

Thermodynamic, electronic and structural properties of Cu/CeO2 surfaces and interfaces from first-principles DFT+U calculations

The thermodynamic, structural and electronic properties of Cu-CeO(2) (ceria) surfaces and interfaces are investigated by means of density functional theory (DFT+U) calculations. We focus on model systems consisting of Cu atoms (i) supported by stoichiometric and reduced CeO(2) (111) surfaces, (ii) dispersed as substitutional solid solution at the same surface, as well as on (iii) the extended Cu(111)/CeO(2)(111) interface. Extensive charge reorganization at the metal-oxide contact is predicted for ceria-supported Cu adatoms and nanoparticles, leading to Cu oxidation, ceria reduction, and interfacial Ce(3+) ions. The calculated thermodynamics predict that Cu adatoms on stoichiometric surfaces are more stable than on O vacancies of reduced surfaces at all temperatures and pressures relevant for catalytic applications, even in extremely reducing chemical environments. This suggests that supported Cu nanoparticles do not nucleate at surface O vacancies of the oxide, at variance with many other metal/ceria systems. In oxidizing conditions, the solid solutions are shown to be more stable than the supported systems. Substitutional Cu ions form characteristic CuO(4) units. These promote an easy and reversible O release without the reduction of Ce ions. The study of the extended CeO(2)(111)/Cu(111) interface predicts the full reduction of the interfacial ceria trilayer. Cu nanoparticles supported by ceria are proposed to lie above a subsurface layer of Ce(3+) ions that extends up to the perimeter of the metal-oxide interface.     

TiN_(0.3)/CeO_2光阳极材料的构筑及其光电催化性能(英文)

采用高温氮化法在Ti片基底上生长一层TiN0.3薄膜,进一步利用电化学沉积法在TiN0.3薄膜上生长CeO2,制备了TiN0.3/CeO2复合材料.分别用X射线衍射和扫描电镜研究了复合材料的晶体和形貌结构,用紫外-可见光谱探究了材料的光学吸收性能.结果表明,球状CeO2颗粒均匀地分布在TiN0.3表面;该复合光阳极除了TiN0.3对可见光的吸收外,外层的CeO2同时实现了对紫外光的吸收.光电催化性能研究发现,TiN0.3/CeO2复合光阳极能够显著提高TiN0.3或CeO2的光电流密度,同时增加光电流的稳定性.TiN0.3/CeO2独特的双层结构是其光电催化性能提高的主要原因.在TiN0.3与CeO2界面处异质结构的驱动下,CeO2层中的光生电子迁移至TiN0.3层,而相应的光生空穴在界面处被Ce3+所消耗,从而提高了CeO 2层中电子和空穴的分离效率,光电流密度也随之提高;同时,位于CeO2与电解液界面处的Ce3+作为水分子的吸附中心和反应活性中心,加快了界面处水的氧化反应,从而进一步促进了稳定光电流的产生.鉴于TiN0.3/CeO2光阳极材料优良的光电催化性能,其在太阳能光电催化领域具有潜在的应用,对于新型高效光电转化材料的设计与合成具有借鉴作用.     

纳米CeO2基固溶体催化柴油机碳颗粒物燃烧性能

采用柠檬酸溶胶鄄凝胶法制备CeO2基固溶体催化剂(Ce0.7Zr0.3O2-δ、Ce0.7Pr0.3O2-δ和Ce0.7Gd0.3O2-δ), 并考察了固溶体和三种常用载体(TiO2、SiO2和Al2O3)及其负载KNO3后的催化碳黑燃烧活性. 结果表明, CeO2基固溶体催化剂具有很高的催化燃烧活性, 其活性接近TiO2、SiO2和Al2O3负载30%KNO3催化剂的活性. 因为纳米CeO2基固溶体的形成, 提高了催化剂的抗烧结能力, 使氧更活泼, 从而提高氧化还原性能, 有利于碳颗粒燃烧. 由于CeO2基固溶体本身的高活性, 因此KNO3的添加不能明显提高CeO2基固溶体催化剂(尤其是Ce0.7Zr0.3O2-δ和Ce0.7Pr0.3O2-δ)的催化燃烧活性, 但KNO3能显著提高TiO2, SiO2和Al2O3的催化燃烧活性.     

氧化铈纳米粒子光催化降解亚甲基蓝的动力学和机理

 CeO2 nanocrystals were synthesized by a simple precipitation method and calcination at 600 °C. (NH4)2Ce(NO3)6 and ammonia were used as precursors. The CeO2 nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and N2 adsorption. The photodegradation of methylene blue catalyzed by CeO2 nanoparticles was studied under UV and sunlight irradiation. The highest degradation was obtained with 1.0 g/L CeO2 at pH 11 within 125 min. The pseudo first order rate constants of dye bleaching were calculated as 16.2x10-3 and 15.7x10-3 min-1 under UV and sunlight irradiation, respectively. The effect of iso-PrOH, iodide ion, and H2O2 was studied to predict the pathway of dye degradation. The obtained results indicate the effect of photogenerated holes in the degradation mechanism of the dye. Also, the photocatalytic activity of the prepared photocatalyst was studied in the presence of several negative ions.     

二氧化铈-铈掺杂锰氧化物纳米复合物高效紫外-可见-红外光热催化净化乙酸乙酯

乙酸乙酯是一种重要的有机溶剂,广泛应用于涂料、粘合剂和塑料及石化等工业生产,但作为一种主要的挥发性有机污染物(VOCs),其对大气环境造成严重污染.目前工业上主要采用负载型贵金属催化剂催化燃烧的方法进行净化处理,但该方法存在催化剂价格昂贵和能耗高的问题,迫切需要开发活性高、稳定性好、成本低及能耗小的催化新方法和新材料....     

The Vital Role of Buffer Anions in the Antioxidant Activity of CeO(2) Nanoparticles

Cerium oxide (CeO(2) ) nanoparticles display excellent antioxidant properties by scavenging free radicals. However, some studies have indicated that they can cause an adverse response by generating reactive oxygen species (ROS). Hence, it is important to clarify the factors that affect the oxidant/antioxidant activities of CeO(2) nanoparticles. In this work, we report the effects of different buffer anions on the antioxidant activity of CeO(2) nanoparticles. Considering the main anions present in the body, Tris-HCl, sulfate, and phosphate buffer solutions have been used to evaluate the antioxidant activity of CeO(2) nanoparticles by studying their DNA protective effect. The results show that CeO(2) nanoparticles can protect DNA from damage in Tris-HCl and sulfate systems, but not in phosphate buffer solution (PBS) systems. The mechanism of action has been explored: cerium phosphate is formed on the surface of the nanoparticles, which interferes with the redox cycling between Ce(3+) and Ce(4+) . As a result, the antioxidant activity of CeO(2) nanoparticles is greatly affected by the external environment, especially the anions. These results may provide guidance for the further practical application of CeO(2) nanoparticles.     

负载型铈基催化剂在NH3-SCR反应中的载体效应

近年来,氨-选择催化还原(NH3-SCR)技术被公认为是控制燃煤烟气和柴油车尾气氮氧化物(NOx)排放的最有效手段之一.V2O5-WO3/TiO2和V2O5-MoO3/TiO2催化剂在300–400°C范围内表现出优异的脱硝性能和抗H2O和SO2中毒性能,因而被广泛用于NH3-SCR过程.然而,钒基催化剂存在一些缺点,如氧化SO2到SO3的活性较高、高温下将部分NH3非选择性地氧化成N2O、V2O5具有生物毒性等.因此,非钒基脱硝催化剂的研制引起人们越来越多的关注.二氧化铈(CeO2)因具有氧化还原性能优异、储/释氧能力强和Ce3+/Ce4+转换容易等优点而广泛用于NH3-SCR反应.然而,单纯CeO2的脱硝性能并不理想.研究表明,将CeO2制备成铈基复合金属氧化物催化剂和负载型铈基催化剂可显著提高其在NH3-SCR反应中的催化性能.尤其是负载型铈基催化剂由于催化性能优异、比表面积大、热稳定性高及活性组分用量少而成为研究热点.众所周知,对于负载型金属氧化物催化剂,载体并不只是惰性材料,它会显著影响表面负载组分的物理化学性质和催化性能.因此,关于载体与组分间相互作用的研究常见诸报道.但是,对于负载型铈基催化剂,具有不同晶相结构的载体对其理化性质和NH3-SCR催化性能的影响规律尚不明晰.此外,SiO2,γ-Al2O3,ZrO2和TiO2是工业上常用的四种催化剂载体,它们具有不同的晶相结构和应用场合,究竟哪一个最适合作为负载型铈基催化剂的载体用于NH3-SCR反应尚无定论.因此,为了阐明负载型铈基催化剂在NH3-SCR反应中的载体效应,筛选出最佳的催化剂载体,我们首先采用溶胶-凝胶法和沉淀法合成了SiO2,γ-Al2O3,ZrO2和TiO2四个载体,再通过浸渍法制备了一系列负载型铈基催化剂(CeO2/SiO2,CeO2/γ-Al2O3,CeO2/ZrO2和CeO2/TiO2)用于NH3-SCR反应.并借助于X射线衍射(XRD)、拉曼光谱(Raman)、比表面积测定(BET)、X射线光电子能谱(XPS)、氢气-程序升温还原(H2-TPR)以及氨气-程序升温脱附(NH3-TPD)等表征手段对上述载体和催化剂进行了较为全面的分析.研究结果表明,这些负载型铈基催化剂的理化性质和脱硝性能强烈地依赖于催化剂载体.首先,CeO2/γ-Al2O3催化剂的表面Ce3+含量明显大于CeO2/SiO2,CeO2/ZrO2和CeO2/TiO2催化剂,有利于氧空位的产生以促进NO分子的解离,进而导致优异的NH3-SCR反应性能.其次,CeO2/γ-Al2O3催化剂具有最佳的还原性能,有利于NO氧化为NO2,进而通过"快速NH3-SCR"途径提升其催化性能.再者,CeO2/γ-Al2O3催化剂表面酸性位最多,能够促进反应物NH3分子的吸附与活化,从而提高脱硝性能.最后,CeO2/γ-Al2O3催化剂在H2O和SO2存在的条件下同样表现出最佳的催化性能,表明其有望用于实际燃煤烟气脱硝.     

Al合金表面Ce转化膜成膜机理研究

Ce转化膜作为一种Cr转化膜的理想替代品而日益受到人们的重视，但其成膜机理还不很清楚.本文应用自行研制的扫描微参比电极技术（SMRE），原位测量经CeCl3溶液处理的2024-T3 Al合金表面微区电位分布，并结合X光电子能谱（XPS）和交流阻抗谱（EIS），对Ce转化膜的成膜机理进行探讨.结果表明，在CeCl3溶液中，Ce转化膜的形成过程是 Ce3＋和Cl－相互竞争的动态过程.当由Cl－的不均匀吸附引起的局部腐蚀使pH升高时， Ce(OH)3就会首先在局部位置发生沉积.阴极反应过程产生的H2O2可将Ce(OH)3部分氧化成CeO2.     

Co3O4/CeO2的氧化还原性能及反应条件对其CO氧化活性的影响

采用沉淀氧化法制备了Co₃O₄/CeO₂催化剂。运用XRD、BET和TPR表征手段,考察了不同钴铈比及焙烧温度对钴铈复合氧化物物理及化学性能的影响,并分别在干、湿条件下进行了一氧化碳氧化反应研究。结果表明,与纯的Co₃O₄相比,在不同比例的Co₃O₄/CeO₂均经723 K焙烧的各种催化剂中,钴铈原子比为9∶1的复合氧化物粒径较小,比表面积较大,说明适当比例铈的添加能使Co₃O₄具有较小的粒径。此氧化物经538 K温度焙烧制得的钴铈比为9∶1的复合氧化物中Co₃O₄平均粒径为7.2 nm, BET比表面积为167.6 m²/g。经TPR考察发现其具有最优的氧化还原性能。     

Direct evidence of redox interaction between metal ion and support oxide in Ce(0.98)Pd(0.02)O(2-δ) by a combined electrochemical and XPS study

A combined electrochemical method and X-ray photo electron spectroscopy (XPS) has been utilized to understand the Pd(2+)/CeO(2) interaction in Ce(1-x)Pd(x)O(2-δ) (x = 0.02). A constant positive potential (chronoamperometry) is applied to Ce(0.98)Pd(0.02)O(2-δ) working electrode which causes Ce(4+) to reduce to Ce(3+) to the extent of ~35%, while Pd remains in the +2 oxidation state. Electrochemically cycling this electrode between 0.0-1.2 V reverts back to the original state of the catalyst. This reversibility is attributed to the reversible reduction of Ce(4+) to Ce(3+) state. CeO(2) electrode with no metal component reduces to CeO(2-y) (y~0.4) after applying 1.2 V which is not reversible and the original composition of CeO(2) cannot be brought back in any electrochemical condition. During the electro-catalytic oxygen evolution reaction at a constant 1.2 V for 1000 s, Ce(0.98)Pd(0.02)O(2-δ) reaches a steady state composition with Pd in the +2 states and Ce(4+): Ce(3+) in the ratio of 0.65:0.35. This composition can be denoted as Ce(4+)(0.63)Ce(3+)(0.35)Pd(0.02)O(2-δ-y) (y~0.17). When pure CeO(2) is put under similar electrochemical condition, it never reaches the steady state composition and reduces almost to 85%. Thus, Ce(0.98)Pd(0.02)O(2-δ) forms a stable electrode for the electro-oxidation of H(2)O to O(2) unlike CeO(2) due to the metal support interaction.     

铈基与钴基Co3O4-CeO2氧载体上甲烷化学链转化特性: 产物选择性控制

采用水热法制备了Co₃O₄/CeO₂(x)[x为钴铈原子摩尔比n(Co):n(Ce)=6:49:1]和Ce_1-yCo_yO_2-δ(y=0.10.4)2个系列复合氧化物, 并表征了材料的物理化学性质, 考察了这些氧化物作为氧载体参与甲烷化学链转化(化学链燃烧和化学链部分氧化)的反应性能. 结果表明, 2类复合氧化物的甲烷反应活性均明显优于单一氧化物CeO₂或Co₃O₄, 但2类氧载体上的甲烷反应产物的选择性具有明显差异. Ce_1-yCo_yO_2-δ氧载体形成了Ce-Co-O固溶体, 储氧能力明显增强, 体相晶格氧迁移速率与甲烷活化速率匹配较好, 甲烷反应产物以CO和H₂的合成气为主, 有利于甲烷的化学链部分氧化. Co₃O₄/CeO₂(x)氧载体中CeO₂与Co₃O₄之间的相互作用改善了材料的储氧能力和氧化活性, 其与甲烷反应时主要生成CO₂, 有利于甲烷化学链燃烧. 连续性化学链循环实验表明, 2类氧载体均具有较好的再生性能和循环稳定性.     

Nanostructured oxide-based powders: investigation of the growth mode of the CeO2 clusters on the YSZ surface

CeO(2)/YSZ nanocomposite powders, characterized by increasing Ce/Zr atomic ratio, were obtained by depositing, by wet impregnation, different amounts of CeO(2) on the yttria-stabilized zirconia (YSZ) surface. These powders were characterized by means of X-ray photoelectron spectroscopy, transmission electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Experimental results allow us to obtain interesting information concerning the growth mode, the morphology, and the dimensions of the CeO(2) clusters on the YSZ supporting surface. A 3-D growing mechanism was observed for the CeO(2) nanoparticles. With increasing Ce/Zr atomic ratio the CeO(2) clusters become more and more spherical. Moreover, XPS data also show the presence of Ce(III) and Ce(IV) ions at the interface supported/supporting oxides.     

氮气气氛下焙烧的CeO_2载体负载Ni基催化剂的顺酐加氢性能研究

在氮气气氛中合成了具有较高氧缺陷浓度的CeO_2载体,采用浸渍法制备了Ni含量为10%的Ni/CeO_2-N催化剂,考察了其顺酐液相加氢性能,并与氧气气氛中制得的CeO_2载体负载Ni催化剂作了对比.N_2低温物理吸脱附,X-射线衍射,拉曼光谱,H_2程序升温还原等表征手段表明,在氮气气氛中合成的CeO_2具有较高浓度的氧缺陷位,在催化剂还原过程中可促进NiO物种的还原,同时在催化剂表面生成更多的氧缺陷位.该氧缺陷位可与活性金属Ni物种协同作用,显著提高催化剂的C=C及C=O加氢活性.     

La-Ce-Cu系列催化剂SO2中毒机理研究

采用NH_4NO_3共熔法合成La－Ce－Cu系列样品，并通过XRD分析了样品的相组成。XRF证明了系列样品组成均为氧缺陷型化合物．用TEM研究了样品的表面结构，发现随着SO_2中毒的加深，Cu向表面偏析与S结合生成新的化合物，导致了原晶体结构的变形，同时证明纯CeO_2不发生S中毒．XPS研究表明：样品La_(.029)Ce_(0.57)Cu_(0.14)O_x中毒后Cu从La_2CuO_4中分解出来并与S结合生成CuSO_4；相应的CeO_2参与了中毒反应，生成Ce_2O_3,整个中毒反应如下：La_2CuO_4＋2CeO_2＋SO_2＝CuSO_4＋La_2O_3＋Ce_2O_3     

Structural characterization of nanosized CeO(2)-SiO(2), CeO(2)-TiO(2), and CeO(2)-ZrO(2) catalysts by XRD, Raman, and HREM techniques

Structural characteristics of nanosized ceria-silica, ceria-titania, and ceria-zirconia mixed oxide catalysts have been investigated using X-ray diffraction (XRD), Raman spectroscopy, BET surface area, thermogravimetry, and high-resolution transmission electron microscopy (HREM). The effect of support oxides on the crystal modification of ceria cubic lattice was mainly focused. The investigated oxides were obtained by soft chemical routes with ultrahighly dilute solutions and were subjected to thermal treatments from 773 to 1073 K. The XRD results suggest that the CeO(2)-SiO(2) sample primarily consists of nanocrystalline CeO(2) on the amorphous SiO(2) surface. Both crystalline CeO(2) and TiO(2) anatase phases were noted in the case of CeO(2)-TiO(2) sample. Formation of cubic Ce(0.75)Zr(0.25)O(2) and Ce(0.6)Zr(0.4)O(2) (at 1073 K) were observed in the case of the CeO(2)-ZrO(2) sample. Raman measurements disclose the fluorite structure of ceria and the presence of oxygen vacancies/Ce(3+). The HREM results reveal well-dispersed CeO(2) nanocrystals over the amorphous SiO(2) matrix in the cases of CeO(2)-SiO(2), isolated CeO(2), and TiO(2) (anatase) nanocrystals, some overlapping regions in the case of CeO(2)-TiO(2), and nanosized CeO(2) and Ce-Zr oxides in the case of CeO(2)-ZrO(2) sample. The exact structural features of these crystals as determined by digital diffraction analysis of HREM experimental images reveal that the CeO(2) is mainly in cubic fluorite geometry. The oxygen storage capacity (OSC) as determined by thermogravimetry reveals that the OSC of the mixed oxide systems is more than that of pure CeO(2) and is system dependent.     

Cerium dioxide/polyaniline core-shell nanocomposites

The preparation of CeO2/polyaniline (CeO2/PANI) core-shell nanocomposites via chemical oxidation of aniline using CeO2 as an oxidant is reported. TEM, TGA, FT-IR, XPS, and conductivity measurement are used to characterize the resulting composites. TEM measurements reveal that the shape of PANI/CeO2 nanocomposites is different from CeO2 nanoparticles and fibular PANI oxidized with soluble oxidant. Electron diffraction (ED) patterns of CeO2/PANI nanocomposites reveal single crystal of CeO2. FT-IR spectra confirmed the formation of PANI; the amount of PANI in the nanocomposites is estimated by TGA results. The conductivities increase with the increasing ratio of PANI/CeO2. XPS results reveal that in the nanocomposites Ce4+ of CeO2 is reduced to Ce3+. In addition, the degree of protonation of polyaniline obtained from N 1s XPS results in cerium dioxide/polyaniline composites is about 48.52%.